Endoscope, endoscopic head, and method for producing an endoscope

ABSTRACT

An endoscope according to the invention comprises an endoscope shaft (3), which has a cylindrical shaft tube (4), and an endoscope head (2), which is arranged at a proximal end of the endoscope shaft (3) and, in a distal end region (11), has a cylindrical interior (13) with a peripheral groove (15), wherein the shaft tube (4) is inserted into the cylindrical interior (13) and folded into the peripheral groove (15). According to the invention, the groove (15) is not rotationally symmetrical. The invention further relates to an endoscope head and to a method for producing an endoscope.

The present invention relates to an endoscope according to the preambleof claim 1, to an endoscope head, and to a method for producing anendoscope.

Endoscopes are used to view cavities in the human or animal body andalso in technical objects. An endoscope typically comprises an elongatecylindrical endoscope shaft, which is suitable for insertion into thecavity to be viewed, and an endoscope head which is arranged at theproximal end of the endoscope shaft (i.e. the end near the user), isconnected rigidly to the proximal end region of the endoscope shaft andcan have attachments and control elements and also an eyepiece lens.Inside the endoscope shaft and the endoscope head there is an opticalsystem for transmitting an endoscopic image from the distal end of theendoscope (i.e. the end remote from the observer) to the proximal end.

During their use, endoscopes are exposed to considerable mechanical andthermal stresses. There are therefore strict requirements regarding thestrength of the connection between the endoscope head and the endoscopeshaft. Axial forces and also transverse forces have to be able to betaken up, and a rotation of the endoscope shaft relative to theendoscope head about the longitudinal axis of the endoscope head mustalso be prevented.

In order to connect the endoscope shaft firmly to the endoscope head ina simple way, it is known from EP 1 872 706 A1 to push the proximal endregion of an optic tube of the endoscope shaft into the distal endregion of the endoscope head and to press-fit it to the latter bycompression, wherein the distal end region of the endoscope head isprovided on its inside with a circumferential indentation into whichmaterial of the optic tube flows with a form fit during the pressingoperation. The indentation is provided as a groove extending about thefull circumference, such that a particularly large amount of materialcan engage in the indentation and the connection of the endoscope headto the optic tube is therefore particularly stable. To prevent the optictube from being able to rotate relative to the endoscope head about itslongitudinal axis, the distal end region of the endoscope head isprovided with a circumferentially limited recess into which material ofthe optic tube flows with a form fit during the pressing operation.

In the endoscope known from EP 1 872 706 A1, the anti-rotation effectthat is achievable by the material flowing into the cavity is not alwaysoptimal. Moreover, several works steps are required for introducing thefully circumferential groove and the recess into the endoscope head,thereby increasing the manufacturing costs.

The object of the present invention is to make available an endoscopeand an endoscope shaft, and also a method for producing such aendoscope, wherein the abovementioned disadvantages are avoided as faras possible.

This object is achieved by an endoscope according to claim 1, by anendoscope head according to claim 11, and by a method according to claim12.

Advantageous developments are set out in the subclaims.

An endoscope according to the invention comprises a typically elongateendoscope shaft, and an endoscope head arranged at a proximal end of theendoscope shaft. The endoscope shaft has a substantially cylindricalshaft tube which can accommodate, for example, an objective lens forcapturing an endoscopic image and an image carrier for conveying theendoscopic image to the proximal end, it being possible for these to bearranged in an inner tube extending inside the shaft tube. However, itis also possible, for example, for an electronic image-capturing devicewith corresponding electrical leads to be arranged in the shaft tube.Moreover, illumination light guides can extend inside the shaft tube.The shaft tube is in particular an outer tube of the endoscope shaft.The endoscope head can have an eyepiece optics unit and a proximallyarranged eyepiece, or an attachment for connecting to an endoscopecamera. An endoscope of this kind is also referred to as an endoscopeoptic and the endoscope head as an optics head. The endoscope isconfigured in particular as a rigid endoscope with a rigid endoscopeshaft or a rigid cylindrical shaft tube.

In a distal end region, the endoscope head has an at least partiallycylindrical interior into which a proximal end region of the shaft tubeis inserted. For this purpose, the endoscope head can have a housingwith a distal end portion which has a cylindrical or conicalconfiguration on the outside and inside which the cylindrical interioris formed. The cylindrical interior can be a bore in the housing. Theaxis of the cylindrical interior is substantially coincident with alongitudinal axis of the endoscope shaft. The inner surface of theendoscope head, forming the cylindrical interior, has a peripheralgroove. The groove can be formed, for example, by rotation of acorresponding tool, which generates an indentation in the surface of thecylindrical interior, and can also be designated as a fullycircumferential indentation. The shaft tube is inserted with itsproximal end region into the cylindrical interior and folded into theperipheral groove. This means that material of the shaft tube engageswith a form fit in the groove, preferably about the entire circumferenceof the shaft tube, such that the shaft tube is connected to theendoscope head with form-fit engagement. The shaft tube can bepress-fitted to the endoscope head, for example by compression in thelongitudinal direction, and thus be folded into the groove.

According to the invention, the peripheral groove is not rotationallysymmetrical with respect to an axis of the cylindrical interior, whichcorresponds at least approximately to a longitudinal axis of thecylindrical shaft tube inserted therein. This means in particular thatthe groove is formed circumferentially with a non-uniform depth and/orwidth and/or axial position of the groove. There is therefore at least astarting position in which the groove has a first depth and a firstwidth and is arranged at an axial position. There is moreover at least asecond circumferential position of the groove, in which the latter has asecond depth and a second width and is arranged at a second axialposition with respect to the axis of the interior. According to theinvention, the groove is therefore configured in particular in such away that the first depth is not equal to the second depth and/or thefirst width is not equal to the second width and/or the first axialposition is not equal to the second axial position. The groovepreferably has at least one width that corresponds to twice the wallthickness of the shaft tube in the proximal end region of the latter.

The shaft tube and the interior each have a substantially circular crosssection, such that, without anti-rotation means, the endoscope shaftcould rotate in relation to the endoscope head about the longitudinalaxis. By virtue of the fact that the peripheral groove of the interiorof the endoscope head is not rotationally symmetrical, it is possible tosecure against rotation of the shaft tube inserted into the endoscopehead. In particular, in a single work operation, the peripheral groovecan be introduced into the inner surface of the endoscope head formingthe cylindrical interior, and, by press-fitting the shaft tube to theendoscope head, a firm connection can be obtained, which at the sametime secures against rotation. During press-fitting, for example bycompression of the shaft tube by a sufficient amount, an outer fold ofthe shaft tube forms which engages with a form fit in the groove and islikewise not rotationally symmetrical. It is thus possible, by form-fitengagement, to secure particularly effectively against rotation.

The groove preferably has a non-uniform depth about the circumference,i.e. the groove has a first depth in a first circumferential positionand has a second depth in a second circumferential position, wherein thefirst depth is greater than the second depth. The depth of the groove isin each case measured starting from an inner surface of the endoscopehead forming the cylindrical interior. With respect to the axis of thecylindrical interior, the groove can extend substantially in a planeperpendicular to the axis. The fold, with which the shaft tube engagesin the groove, preferably reaches as far as the bottom of the groove, inparticular substantially in the entire peripheral groove or at least ina region extending across a minimum of the depth of the groove.Particularly preferably, the peripheral groove additionally has anon-uniform width about the circumference. By virtue of the fact thatthe groove has a non-uniform depth about the circumference, it ispossible to achieve a particularly simple and effective means ofpreventing rotation of the shaft tube relative to the endoscope head.

A maximum depth of the groove, achieved about the circumference of thegroove, is preferably about twice as great as a minimum depth of thegroove. For example, the maximum depth can be approximately 0.4 mm andthe minimum depth approximately 0.2 mm. Particularly reliable preventionof rotation can be achieved in this way.

The peripheral groove can advantageously be formed with a plurality ofdepth maxima distributed about the circumference and, preferably lyingcentrally between these, a plurality of depth minima. Thus, in a crosssection of the endoscope head, a bottom of the groove can form a closedcurve in the shape of a polygon, preferably with rounded corners andcurved sides. The depth maxima can each have an identical depth.

Likewise, the depth minima can each have an identical depth. Thispermits simple production and at the same time permits a secureconnection of the shaft tube to the endoscope head, wherein play of theshaft tube in the endoscope head can be avoided with increasedcertainty. Alternatively, provision can be made that the groove has asingle depth maximum and, preferably lying opposite this, a single depthminimum.

Particularly preferably, the groove has three depth maxima arrangedapproximately with a spacing of 120° along the circumference, and alsothree depth minima arranged approximately centrally between the depthmaxima. In a cross section of the endoscope head, the bottom of thegroove thus constitutes a triangle-shaped curve, preferably with roundedcorners and outwardly curved sides. In this way, play of the shaft tuberelative to the endoscope head can be avoided particularly reliably.Alternatively, it is possible to provided two depth maxima and two depthminima, or four depth maxima and four depth minima.

In a further advantageous embodiment, the groove can be configured insuch a way that, in a cross section of the endoscope shaft, i.e. in asection plane perpendicular to the axis of the cylindrical interior, abottom of the groove forms a continuous outward curve, that is to saythe bottom has peripherally a concave shape. This on the one handpermits particularly simple manufacture of the endoscope head with theperipheral groove introduced into the surface of the interior and, onthe other hand, ensures that the shaft tube is folded into the groovesubstantially about the entire circumference and for example engages inthe latter as far as the bottom of the groove about the entirecircumference.

According to a preferred embodiment of the invention, the groove has atrapezoid cross section. A cross section of the groove, extending in aplane substantially perpendicular to the axis of the cylindricalinterior, corresponds to a longitudinal section running through theendoscope head parallel to the axis of the cylindrical interior. Atrapezoid groove allows particularly straightforward production, forexample by means of a suitably guided trapezoid milling cutter, and theformation of a particularly firm connection between the shaft tube andthe endoscope head.

Preferably, the inclination of the flanks of the trapezoid groovemeasures approximately 60° to the longitudinal axis of the cylindricalinterior. More preferably, a bottom of the groove is oriented inlongitudinal section parallel to the axis of the cylindrical interiorand therefore parallel to the surface of the interior. The width of thebottom of the groove can be at least approximately constant incircumference, such that, with a constant angle of inclination of theflanks of the trapezoid groove, the width of the groove measured at thesurface of the interior is circumferentially non-uniform, i.e. at amaximum in circumferential positions of maximum depth and at a minimumin circumferential positions of minimal depth. This not only permitsparticularly straightforward production but also facilitates the foldingof the shaft tube into the groove upon compression.

More preferably, the shaft tube is folded into the groove in such a waythat the fold of the shaft tube, i.e. the material of the shaft tubeengaging in the groove, substantially fills the groove or at leasttouches the bottom or both flanks of a trapezoid groove. Particularlypreferably, the fold substantially fills the groove in allcircumferential positions or at least in circumferential regions thatcomprise the depth minima or extend beyond these. Depending on theprocess sequence, the fold with which the shaft tube engages in thegroove can be a straight/vertical fold or can also be oblique to theaxis of the interior or even horizontal. The shape of the fold candepend on the depth of the groove and can be non-uniform about thecircumference. Thus, in circumferential positions where the groove isdeeper, the fold can have a different shape than it has where the grooveis shallower. For example, where the groove is deeper, the wall of theshaft tube can be less tightly folded together and fill the groove lessfully than it does where the groove has a shallower depth. By virtue ofthe fact that the fold of the shaft tube, engaging in the groove andgenerated by the press-fitting, substantially fills the groove or atleast touches the bottom or both flanks of the groove, rotation can beparticularly reliably prevented, wherein at the same time a play of theshaft tube relative to the endoscope head can be reliably avoided.

According to a preferred embodiment of the invention, a longitudinalgroove is arranged in the inner surface of the endoscope head formingthe cylindrical interior, which longitudinal groove is connected to theperipheral groove and extends beyond the latter in the axial direction,wherein the longitudinal groove is deeper than the peripheral groove inthe connecting region. The longitudinal groove is preferably open in theaxial direction and closed in the distal direction. The longitudinalgroove can also be designated as a cavity of the interior. Thelongitudinal groove, which opens into the peripheral groove and engagesover the latter, permits the introduction of adhesive which can be drawnby capillary forces between the outer surface of the shaft tube and theinner surface of the endoscope head. The adhesive permits a liquid-tightand vapor-tight connection of the shaft tube to the endoscope head andcan additionally secure against rotation. Moreover, when the shaft tubeis press-fitted to the optics head, material can penetrate into thelongitudinal groove, such that this likewise can provide additionalsecuring against rotation.

An endoscope head according to the invention is configured in particularas an endoscope head for a rigid endoscope with a rigid shaft which hasa rigid cylindrical shaft tube. The endoscope head has a housing which,in a distal end region, has a cylindrical interior configured to receivea proximal end region of the shaft tube. The housing of the endoscopecomprises, for example, a cylindrically or conically shaped distal endportion inside which the cylindrical interior is formed. The innersurface of the endoscope head, forming the cylindrical interior, has aperipheral groove. According to the invention, the groove is notrotationally symmetrical with respect to a longitudinal axis of thecylindrical interior. It is thus easily possible to connect the shafttube of the endoscope to the distal end region of the endoscope head bypress-fitting and at the same time to secure against rotation.

In particular the groove is configured as described above, for examplewith a circumferentially non-uniform depth in a plane transverse to theaxis of the cylindrical interior. The peripheral groove can, forexample, have a trapezoid cross section with a circumferentiallyconstant inclination of the flanks. To introduce such a groove, whichhas a non-uniform depth and also a non-uniform width about thecircumference, into the surface of the cylindrical interior of theendoscope head, a suitably shaped milling cutter can be moved along acorresponding curve inside the interior. In addition, the interior canhave a longitudinal groove which is configured as described above andwhich, for example, can be generated by longitudinal milling. Theendoscope head is in particular an endoscope head of an endoscopeconfigured as described above.

In a method according to the invention for producing an endoscope, asubstantially cylindrical shaft tube and an endoscope head are madeavailable, the latter having, in a distal end region, a cylindricalinterior with a peripheral, non-rotationally symmetrical groove.Moreover, a proximal end region of the shaft tube is pushed into thecylindrical interior of the endoscope head, and the proximal end regionof the shaft tube is press-fitted to the distal end region of theendoscope head, in particular by compression of the shaft tube. In thisway, the shaft tube is folded into the peripheral groove and connectedwith form-fit engagement to the distal end region of the endoscope head.The production method can comprise further steps, for example theintroduction of optical and/or electronic elements into the shaft tubeand the endoscope head.

The press-fitting is preferably carried out by compression of the shafttube. The shaft tube is compressed by such an amount that material ofthe shaft tube penetrates into the groove at least in sections,preferably about the entire circumference, and touches at least bothflanks or the bottom. The press-fitting can be carried out by coldpressing.

Further features of the endoscope, of the endoscope head and of theproduction method are disclosed in EP 1 872 706 A1, which document is inthis respect incorporated by reference into the present application.

It goes without saying that the aforementioned features and the featuresstill to be explained below can be used not only in the respectivelycited combination but also in other combinations or singly, withoutdeparting from the scope of the present invention.

Further aspects of the invention will become clear from the followingdescription of a preferred illustrative embodiment and from the attacheddrawing, in which:

FIG. 1 shows an illustrative embodiment of an endoscope according to theinvention in an overall view;

FIG. 2 shows a longitudinal section through a part of the housing of anendoscope head and the proximal end region of the shaft tube of theendoscope according to FIG. 1;

FIG. 3 shows an enlarged detail from FIG. 2;

FIG. 4 shows the peripheral groove of the endoscope head in a schematiccross-sectional view;

FIG. 5 shows a longitudinal section through a part of the housing of theendoscope head with the shaft tube pressed in;

FIG. 6 shows an enlarged detail from FIG. 5;

FIG. 7 shows a schematic cross-sectional view of the peripheral grooveof the endoscope head with the shaft tube pressed in.

As is shown by way of example in FIG. 1, an endoscope 1 according to theinvention comprises an endoscope head 2 and an elongate endoscope shaft3. In the endoscope 1 shown in FIG. 1, which is a rigid endoscope, theendoscope shaft 3 is of rigid configuration and has a shaft tube 4 whichforms the outer tube of the endoscope shaft 3. A proximal end region 5of the shaft tube 4 is fixedly connected to a housing 6 of the endoscopehead 2. At the distal side, the housing 6 has a frustoconical surface 7which serves for connection to the shaft of an endoscopic instrument,for which purpose a locking element 8 is moreover provided. At theproximal side, the housing carries an eyepiece 9. A light attachmentpiece 10 is arranged laterally on the housing 6. Optical components (notshown in the figures) are accommodated inside the endoscope. The shafttube 4 and the housing 6 of the endoscope head 2 are produced fromstainless steel, for example.

FIG. 2 shows the distal region of the housing 6 of the endoscope head 2in longitudinal section. In its distal end region 11, the housing 6 ofthe endoscope head 2 has a cone 12, which on the outside forms thefrustoconical surface 7; the cone 12 can be formed integrally with theother regions of the housing 6. On the inside, the cone 12 has acylindrical interior 13 which extends in the axial direction and is openboth at the distal side and also at the proximal side. The cylindricalinterior 13 can in particular be configured as a through-bore of thecone 12. A peripheral groove 15 is introduced into the inner surface 14of the cone 12 and extends in a plane perpendicular to the axis of theinterior 13. Furthermore, a longitudinal groove 16 is introduced intothe inner surface 14 of the cone 12, which longitudinal groove 16 isopen at the proximal side, but closed at the distal side, andcommunicates with the peripheral groove 15.

FIG. 2 also shows the proximal end region 5 of the shaft tube 4 of theendoscope 1 in longitudinal section. The shaft tube 4 is cylindrical atleast in the proximal end region 5. The external diameter d of the shafttube 4 is not greater than the internal diameter D of the cone 12,preferably slightly smaller than it. The external diameter d of theshaft tube 4 can be 5 mm, for example.

As can be seen from FIG. 3, which shows an enlarged detail of thelongitudinal section according to FIG. 2, the peripheral groove 15 has atrapezoid cross section with a bottom 17 and two oblique flanks 18, 19.The flanks 18, 19 are at an angle of α=60° to each other. In thelongitudinal section shown, which shows the cross section of the groove15, the bottom 17 extends parallel to the axis 20 of the cylindricalinterior 13. The flanks 18, 19 are each at an angle of 60° to the innersurface 14 of the cone 12 and to the bottom 17 of the groove 15. In theillustrative embodiment shown, the groove 15 has a depth of 0.34 mm, andthe bottom 16 has a width b=0.31 mm, in the longitudinal section planeshown.

The shape of the groove 15 is indicated in FIG. 4 in a cross section inthe plane perpendicular to the axis of the interior 13 in which thegroove 15 extends. As is shown in FIG. 4, the groove 15 introduced intothe inner surface 14 of the cone 12 has a non-uniform depth about thecircumference. In the illustrative embodiment shown, the groove 15 hasthree depth maxima 21, 21′, 21″, which are spaced apart from each otherby 120° in each case and between which the depth minima 22, 22′, 22″ arearranged. In the cross-sectional view, the bottom of the groove 15 thushas the shape of a rounded triangle. At the position of a depth minimum22″, the longitudinal groove 16 is introduced into the inner surface 14of the cone 12, which longitudinal groove 16 is connected to theperipheral groove 15 and engages under it, i.e. is deeper than thegroove 15 in the region thereof. In the illustrative embodiment shown,the depth of the groove 15 is approximately 0.4 mm at each of the depthmaxima 21, 21′, 21″ and approximately 0.2 mm at each of the depth minima22, 22′, 22″. The cone 12 is not shown in any detail in FIG. 4.

To assemble the endoscope 1, the proximal end region 5 of the shaft tube4 is inserted from the distal axial direction into the interior 13 untilthe shaft tube 4 protrudes sufficiently beyond the groove 15 in theproximal direction (see FIG. 2). The shaft tube 4 is then pressed intothe distal end region 11 of the endoscope head 6. To do this, the shafttube 4 is compressed in the axial direction, for which purpose it is,for example, clamped distally in a holding device and compressed fromthe proximal direction by means of an inserted mandrel. In this way, theshaft tube 4, which has a suitably small wall thickness, folds into thegroove 15. The shaft tube 4 is compressed to such an extent that thematerial penetrating into the groove substantially fills the groove 15or, at least outside the depth minima 22, 22′, 22″, penetrates deeperinto the groove 15 than the depth of the depth minima 22, 22′, 22″. Forsecure holding of the shaft tube 2 in the cone 12 and therefore for afirm connection of the shaft tube 2 to the endoscope head 6, it isadvantageous if the material of the shaft tube 4 penetrating into thegroove 15 touches at least both flanks 18, 19, and particularlyadvantageously also the bottom 17 of the groove 15, substantially aboutthe entire circumference.

This is shown in FIGS. 5 to 7. As is shown in the longitudinal sectionthrough the distal region of the housing 6 of the endoscope head 2 inFIG. 5, the wall of the shaft tube 4 arranges itself as fold 23 in thegroove 15 when compressed with a suitable tool, for example with asubstantially cylindrical mandrel. The fold 23 fills the groove 15partially or completely and thus fixes the shaft tube 4 in the cone 12.This results in a firm connection between the shaft tube 4 and thehousing 6 of the endoscope head 2 and creates a cavity 24 extending allthe way through the inside of the shaft tube 4 as far as the endoscopehead 2. In particular, the shaft tube 4 is not only held in the cone 12securely with respect to axial stresses and bending stresses, but alsofixed against torsion about the longitudinal axis relative to thehousing 6 of the endoscope head 2.

An enlarged detail of the longitudinal section according to FIG. 5 isshown in FIG. 6. As can be seen from FIG. 6, the fold 23 of the shafttube 4 engages in the groove 15 and substantially fills the latter. Thefold 23 can also penetrate into the longitudinal groove 16, althoughthis is not essential for securing against rotation. The longitudinalgroove 16 is not filled to the bottom.

This is also shown in the cross section shown in FIG. 7, whichcorresponds to the illustration in FIG. 4. The fold 23 fills the groove15 about the entire circumference, including the depth maxima 21, 21′,21″ and the depth minima 22, 22′, 22″, practically as far as the bottom.The longitudinal groove 16 is also partially filled, but not as far asthe bottom, such that a space 25 remains.

In a work step following on from the compression, adhesive can beintroduced into the longitudinal groove from the proximal direction.This adhesive passes through the space 25 to the distal side of the fold23 (see FIG. 6). The adhesive penetrates proximally and distally into agap between the outside of the shaft tube 4 and the inner surface 14 ofthe cone 12, sets therein, and thus permits a liquid-tight andvapor-tight connection of the shaft tube 4 to the housing 6 of theendoscope head 2.

Moreover, as is indicated by the enlarged external diameter d′ in FIG.5, the shaft tube 4 can be widened in a funnel shape at the proximal endby insertion of a corresponding mandrel. Otherwise, the press-fitting ofthe shaft tube 4 to the distal end region of the endoscope head 2 can becarried out in the manner described in EP 1 872 706 A1.

For the sake of clarity, not all the reference signs are shown in all ofthe figures. Reference signs not explained in connection with one figurehave the same meaning as in the other figures.

LIST OF REFERENCE SIGNS

-   1 endoscope-   2 endoscope head-   3 endoscope shaft-   4 shaft tube-   5 proximal end region of the shaft tube-   6 housing-   7 surface-   8 locking element-   9 eyepiece-   10 light attachment piece-   11 distal end region of the endoscope head-   12 cone-   13 interior-   14 inner surface-   15 groove-   16 longitudinal groove-   17 bottom-   18 flank-   19 flank-   20 axis-   21, 21′, 21″ depth maximum-   22, 22′, 22″ depth minimum-   23 fold-   24 cavity-   25 space

1. Endoscope with an endoscope shaft (3), which has a cylindrical shafttube (4), and with an endoscope head (2), which is arranged at aproximal end of the endoscope shaft (3) and, in a distal end region(11), has a cylindrical interior (13) with a peripheral groove (15),wherein the shaft tube (4) is inserted into the cylindrical interior(13) and folded into the peripheral groove (15), characterized in thatthe groove (15) is not rotationally symmetrical.
 2. Endoscope accordingto claim 1, characterized in that the groove (15) has a non-uniformdepth about the circumference.
 3. Endoscope according to claim 2,characterized in that a maximum depth of the groove (15) is about twiceas great as a minimum depth.
 4. Endoscope according to claim 2 or 3,characterized in that the groove (15) has a plurality of depth maxima(21, 21′, 21″) distributed uniformly about its circumference and, lyingbetween these, a plurality of depth minima (22, 22′, 22″).
 5. Endoscopeaccording to claim 4, characterized in that the groove (15) has threedepth maxima (21, 21′, 21″) and three depth minima (22, 22′, 22″). 6.Endoscope according to one of the preceding claims, characterized inthat a bottom (17) of the groove (15) forms a closed, continuouslyconcave curve.
 7. Endoscope according to one of the preceding claims,characterized in that the groove (15) has a trapezoid shape in a crosssection of the groove (15).
 8. Endoscope according to one of thepreceding claims, characterized in that the groove (15) has a bottom(17) and, arranged on both sides, flanks (18, 19), wherein aninclination of the flanks measures approximately 60°.
 9. Endoscopeaccording to one of the preceding claims, characterized in that a fold(23) of the shaft tube (4) substantially fills the groove (15). 10.Endoscope according to one of the preceding claims, characterized inthat the cylindrical interior (13) has a longitudinal groove (16) whichis connected to the peripheral groove (15) and extends beyond the latterin the axial direction, wherein the longitudinal groove (16) is deeperthan the peripheral groove (15) in the connecting region.
 11. Endoscopehead, in particular for a rigid endoscope (1), with a housing (6) which,in a distal end region (11), has a cylindrical interior (13) with aperipheral groove (15), characterized in that the peripheral groove (15)is not rotationally symmetrical.
 12. Method for producing an endoscope,wherein a cylindrical shaft tube (4) and an endoscope head (2) are madeavailable, the latter having, in a distal end region (11), a cylindricalinterior (13) with a peripheral, non-rotationally symmetrical groove(15), a proximal end region (5) of the shaft tube (4) is pushed into thecylindrical interior (13) of the endoscope head (2), and the proximalend region (5) of the shaft tube (4) is press-fitted to the distal endregion (11) of the endoscope head (2).